Conventional electronic device manufacturing systems may include multiple process chambers and load lock chambers. Such chambers may be included in cluster tools where a plurality of process chambers may be distributed about a transfer chamber, for example. These systems and tools may employ articulated multi-link robots, which may be housed within the transfer chamber and transport substrates between the various process chambers and load locks. For example, the robot may transport a substrate from chamber to chamber, from load lock to chamber, and/or from chamber to load lock. Efficient and precise transport of substrates between the various system chambers may be important to system throughput, thereby lowering overall operating costs. Furthermore, precise substrate placement may improve overall processing quality. In many systems, Selective Compliant Articulated Robot Arm (SCARA) robots 100 are employed as shown in FIGS. 1A and 1B. SCARA robots 100 employ three links driven by two motors. The three links comprise an upper arm link 102, a forearm link 104, and a wrist member 106 coupled to a waist 107. An end effector 108 may be coupled to the wrist member 106 and is adapted to carry a substrate 105 to a pick or place destination such as a process chamber 110. The first motor drives the waist 107 thereby allowing overall positioning of the robot 100 in an X-Y plane. The second motor drives all the kinematically-coupled arms 102, 104, 106 such that the wrist member 106 moves linearly away from the waist 107 along a linear axis 112. Problematically, such SCARA robots 100 suffer from a compromise between positional alignment and rotational alignment. For example, due to calibration and/or manufacturing tolerances, the linear axis 112 may be offset from a normal axis 114 of the chamber 110 such as is shown in FIG. 1A. Such positional alignment between the linear axis 112 of the robot 100 and the normal axis 114 of the chamber 110 may be corrected by rotation of the entire SCARA robot 100 relative to the waist 107, but only while introducing rotational error as is shown in FIG. 1B. Likewise rotational error may be corrected, but only by introducing linear positional error. In semiconductor manufacturing, orientation of the substrate within a chamber and from chamber to chamber may be important in terms of processing quality.
Accordingly, improved methods for efficient and precise orientation of substrates are desired.